hydrophobia

Hydrophobia, or fear of water, is a historical term describing a symptom commonly associated with rabies. The condition refers to an extreme aversion to drinking water and an inability to swallow, arising from painful spasms of the throat, pharynx, and larynx when liquids are attempted. This symptom is often accompanied by agitation, hypersalivation, fever, and confusion as the rabies virus affects the central nervous system. In practice, hydrophobia reflects a physiological reflex and nociceptive response rather than a classic anxiety phobia.

Causes and mechanism: Rabies virus enters via animal bite, travels to the central nervous system, and causes encephalitis with brainstem involvement. Throat muscle spasms triggered by swallowing produce a conditioned avoidance of fluids. The term hydrophobia is thus descriptive of the symptom rather than a separate disease.

Diagnosis: In suspected rabies, hydrophobia is one of the clinical signs. Laboratory confirmation includes detection of rabies virus RNA in saliva or a skin biopsy, serology, or detection of viral antigen in brain tissue (typically post-mortem); diagnosis may also rely on epidemiological context.

Treatment and prognosis: There is no effective treatment once the onset of symptoms occurs; survival is rare. Management is supportive care. Prevention is crucial and includes post-exposure prophylaxis with thorough wound cleaning, rabies vaccine, and sometimes rabies immune globulin.

Epidemiology and terminology: The term hydrophobia is largely historical; modern medical literature emphasizes rabies and its neurologic presentation rather than the separate term. It should be distinguished from aquaphobia, an anxiety disorder characterized by a fear of water.